High speed computers have gained wide acceptance, not only as research tools, but also for process and inventory control in industry, and for data storage and decision making purposes in business. The most common form of output device used in conjunction with these computers is the high speed line printer.
A high speed line printer may operate at a rate in excess of one thousand one hundred (1100) lines per minute, and typically employs selected indicia producing characters which strike an inked ribbon which is disposed adjacent to the paper to be printed. The inked ribbon may be on the order of 14 to 17 inches in width, and is typically fabricated from nylon cloth, silk, or the like. Such ribbons often provide between five and six million lines of printing before the ink contained therein is depleted to the point where the printed indicia is not a dense black.
It may be appreciated that in a machine operating at eleven hundred lines per minute, the inked ribbon may become depleted in a relatively short time. Many computer facilities, in which a plurality of line printers are operating, use ten to twenty ribbons daily in normal operation. These ribbons, typically, cost in excess of $20.00 each. After the ink is depleted, the ribbon is typically thrown away. Thus, the cost of new printing ribbons may comprise a substantial portion of the overhead of a line printer.
The prior art discloses machines for re-inking printing ribbons, in the assumption that it is less expensive to re-ink a used ribbon than to purchase a new one. The following U.S. Pat. Nos. comprise the most pertinent prior art: 3,731,649, 3,885,518.
In re-inking a printer ribbon, it is important to minimize the handling of the ribbon in order that labor costs may be minimized. Thus, the re-inking machine must be as automatic as possible. More importantly, the used ribbon must be scanned to determine the integrity of the fabric web, and to detect any holes therein which might cause a misprint, or lack of print, in a portion of the line printer output.
In both of these respects, the performance of prior art printer ribbon re-inking machines has been poor.